1. Field of the Invention
This invention relates to a substrate defect inspection method and substrate defect inspection system, which use defect inspection equipment and defect observation equipment to inspect defects on substrates.
2. Description of the Related Art
As devices have become finer-structured in recent years, substrate defect inspections have been performed using defect observation equipment having a scanning electron microscope (SEM). In such a defect inspection system, for example, substrate defect positions are first detected by defect detection equipment, these defect locations are observed in detail by SEM, and defects are classified. By using such defect detection equipment and defect observation equipment, substrate defect inspection can be performed without taking much time.
However, in the conventional art, adequate resolution could not be obtained from defect observation equipment, and as a result, there was the possibility of reduced precision in substrate defect inspection.
An object of this invention is to provide a substrate defect inspection method and substrate defect inspection system capable of increasing the precision of substrate defect inspection, by raising the resolution of the defect observation equipment.
As a consequence of earnest studies conducted over time, the authors have discovered that when performing substrate defect inspections using defect detection equipment and defect observation equipment, the size of the field of view (FOV) of the scanning electron microscope of the defect observation equipment cannot be made small due to a shift in the coordinate systems of the two pieces of equipment, and because of this it is difficult to raise the resolution of the defect observation equipment. Upon conducting further earnest investigations, this invention was completed, based on the finding that the shift in the coordinate systems of the two pieces of equipment has, in addition to an offset component, a magnification component and a rotation component.
That is, the substrate defect inspection method of a first concept of this invention is characterized in having a step in which a substrate defect position is detected by defect detection equipment, and information containing this defect position is sent to defect observation equipment; a step in which a plurality of measurement points on the substrate are set, and the amounts of positioning shift of each of the measurement points between the coordinate system of the defect detection equipment and the coordinate system of the defect observation equipment are measured; a step in which a defect position correction formula is created having terms for an offset component and a magnification component for the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, based on the amount of position shift for each of the measurement points; a step in which the defect position detected by the defect detection equipment is corrected using the defect position correction formula; and, a step in which an image of the corrected defect position is generated by the scanning electron microscope of the defect observation equipment, and the defect is inspected based on this image data.
By correcting defect positions detected by the defect detection equipment, using a defect position correction formula having terms for an offset component and a magnification component for the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects existing on the substrate can be reduced. As a result, even if the FOV size of the scanning electron microscope is reduced, and the pixel size is made smaller, a defect will be within the FOV during observation of the defect on the substrate. Hence sufficient resolution can be obtained in the defect observation equipment, and the precision of substrate defect inspection can be improved without reducing the throughput of the defect observation equipment.
It is preferred that, in the step in which the amount of position shift of each of the measurement points is measured, at least six measurement points be set on the substrate, and that, in the step in which the defect position correction formula is created, if the defect position in the x-axis direction is X and the defect position in the y-axis direction is Y in the coordinate system of the defect detection equipment, and if, in the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, the x-axis direction offset component constant is a, the x-axis direction magnification component coefficient is b, the x-axis direction rotation component coefficient is c, the y-axis direction offset component constant is d, the y-axis direction magnification component coefficient is e, the y-axis direction rotation component coefficient is f, the amount of position correction in the x-axis direction is dX, and the amount of position correction in the y-axis direction is dY, then using as the defect position correction formula dX=a+b*Xxe2x88x92c*Y, dY=d+e*Y+f*X, the constants a through f are calculated. When using such a defect position correction formula to correct defect positions, the scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects will become smaller, and so the FOV size of the scanning electron microscope can be made still smaller.
The substrate defect inspection method of a second concept of this invention is characterized in having a step in which a substrate defect position is detected by defect detection equipment, and information containing this defect position is sent to defect observation equipment; a step in which a plurality of measurement points on the substrate are set, and the amounts of shift in the positions of each measurement point between the coordinate system of the defect detection equipment and the coordinate system of the defect observation equipment are measured; a step in which a defect position correction formula is created which has terms for the offset component and the rotation component of the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, based on the amounts of shifts in position for each measurement point; a step in which the defect position detected by the defect detection equipment is corrected using the defect position correction formula; and, a step in which an image of the corrected defect position is generated by the scanning electron microscope of the defect observation equipment, and the defect is inspected based on this image data.
By correcting defect positions detected by the defect detection equipment, using a defect position correction formula having terms for an offset component and a rotation component for the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects existing on the substrate can be reduced. As a result, even if the FOV size of the scanning electron microscope is reduced, and the pixel size is made smaller, a defect will be within the FOV during observation of the defect on the substrate. Hence sufficient resolution can be obtained in the defect observation equipment, and the precision of substrate defect inspection can be improved without reducing the throughput of the defect observation equipment.
It is preferred that, in the step in which the amount of position shift of each of the measurement points is measured, at least six measurement points be set on the substrate, and that, in the step in which the defect position correction formula is created, if the defect position in the x-axis direction is X and the defect position in the y-axis direction is Y in the coordinate system of the defect detection equipment, and if, in the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, the x-axis direction offset component constant is a, the x-axis direction magnification component coefficient is b, the x-axis direction rotation component coefficient is c, the y-axis direction offset component constant is d, the y-axis direction magnification component coefficient is e, the y-axis direction rotation component coefficient is f, the amount of position correction in the x-axis direction is dX, and the amount of position correction in the y-axis direction is dY, then using as the defect position correction formula dX=a+b*Xxe2x88x92c*Y, dY=d+e*Y+f*X, the constants a through f are calculated. When using such a defect position correction formula to correct defect positions, the scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects will become smaller, and so the FOV size of the scanning electron microscope can be made still smaller.
The substrate defect inspection system of the first concept of this invention is a substrate defect inspection system comprising defect detection equipment, which detects substrate defect positions, and defect observation equipment, which uses a scanning electron microscope to observe defects detected by the defect detection equipment and performs defect inspections, and which is characterized in that the defect observation equipment has position shift measurement means, which sets a plurality of measurement points on the substrate, and which measures the amounts of shift in position of each of the measurement points between the coordinate system of the defect detection equipment and the coordinate system of the defect observation equipment; correction formula creation means, which creates a defect position correction formula having terms for the offset component and the magnification component of the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, based on the amounts of shift in position for each measurement point; position correction means, which uses the defect position correction formula to correct the defect position detected by the defect detection equipment; and, means to generate an image of the corrected defect position using a scanning electron microscope, and to inspect the defect based on this image data.
Thus by providing position shift measurement means, correction formula creation means and position correction means, a substrate defect inspection method of the above-described first concept can be executed, and as a result the resolution of the defect observation equipment can be raised, and the defect inspection precision can be improved.
It is preferred that the position shift measurement means sets at least six measurement points on the substrate and measures the position shift amount for each point, and that, if the defect position in the x-axis direction is X and the defect position in the y-axis direction is Y in the coordinate system of the defect detection equipment, and if, in the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, the x-axis direction offset component constant is a, the magnification component coefficient is b, the rotation component coefficient is c, the y-axis direction offset component constant is d, the magnification component coefficient is e, the rotation component coefficient is f, the amount of position correction in the x-axis direction is dX, and the amount of position correction in the y-axis direction is dY, then using as the defect position correction formula dX=a+b*Xxe2x88x92c*Y, dY=d+e*Y+f*X, the correction formula creation means calculates the constants a through f. When using such a defect position correction formula to correct defect positions, the scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects will become smaller, and so the FOV size of the scanning electron microscope can be made still smaller.
It is preferred that the defect detection equipment has defect position precision equivalent to that of the defect observation equipment.
It is preferred that the defect detection equipment have image pickup means for image pickup of the substrate, and means for extraction of substrate defect positions based on substrate image pickup data.
The substrate defect inspection system of the second concept of this invention is a substrate defect inspection system comprising defect detection equipment, which detects substrate defect positions, and defect observation equipment, which uses a scanning electron microscope to observe defects detected by the defect detection equipment and performs defect inspections, and which is characterized in that the defect observation equipment has measurement means, which sets a plurality of measurement points on the substrate, and which measures the amounts of shift in position of each of the measurement points between the coordinate system of the defect detection equipment and the coordinate system of the defect observation equipment; correction formula creation means, which creates a defect position correction formula having terms for the offset component and the rotation component of the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, based on the amounts of shift in position for each measurement point; position correction means, which uses the defect position correction formula to correct the defect position detected by the defect detection equipment; and, means to generate an image of the corrected defect position using a scanning electron microscope, and to inspect the defect based on this image data.
Thus by providing position shift measurement means, correction formula creation means and position correction means, a substrate defect inspection method of the above-described second concept can be executed, and as a result the resolution of the defect observation equipment can be raised, and the defect inspection precision can be improved.
It is preferred that the position shift measurement means sets at least six measurement points on the substrate and measures the position shift amount for each point, and that, if the defect position in the x-axis direction is X and the defect position in the y-axis direction is Y in the coordinate system of the defect detection equipment, and if, in the coordinate system of the defect observation equipment with respect to the coordinate system of the defect detection equipment, the x-axis direction offset component constant is a, the magnification component coefficient is b, the rotation component coefficient is c, the y-axis direction offset component constant is d, the magnification component coefficient is e, the rotation component coefficient is f, the amount of position correction in the x-axis direction is dX, and the amount of position correction in the y-axis direction is dY, then using as the defect position correction formula dX=a+b*Xxe2x88x92c*Y, dY=d+e*Y+f*X, the correction formula creation means calculates the constants a through f. When using such a defect position correction formula to correct defect positions, the scattering in the shift between the corrected defect position and the actual defect position for a plurality of defects will become smaller, and so the FOV size of the scanning electron microscope can be made still smaller.
It is preferred that the defect detection equipment has defect position precision equivalent to that of the defect observation equipment.
It is preferred that the defect detection equipment have image pickup means for image pickup of the substrate, and means for extraction of substrate defect positions based on substrate image pickup data.